Dry storage casks (DSCs) store spent nuclear fuel (SNF) at sites contiguous to nuclear power plants (NPPs), known as Interim Spent Fuel Storage Installations (ISFSIs). DSCs can be stored in concrete bunkers, or designed as free-standing or anchored structures. The primary focus of this study is to investigate response of free-standing DSCs under seismic excitation. Recent consideration of DSCs as a potential midterm solution may increase the operating period (initially 20 years) up to 300 years and requires response reevaluation. A longer compliance period results in larger accelerations, and larger vertical-to-horizontal spectral acceleration ratios that could have destabilizing effects on the cask response.
The response of free-standing DSCs under seismic excitations is highly nonlinear, especially under concurrent sliding and rocking motion triggered by multidirectional seismic excitations. It depends on parameters such as aspect ratio, coefficient of friction between cask and foundation pad, and ground motion characteristics, among other factors.
This research presents the investigation on the response of free-standing DSCs under long return period seismic events. Dynamic experimental tests were performed on a 6-degree-of-freedom shake table at the University of Nevada, Reno. Ground motions used for the tests were spectrally matched to spectral acceleration for seismic events of 10,000- and 30,000-year return periods. Experimental results were used to validate finite element (FE) models. The validated models were then be used to study casks’ response under full intensity long-term seismic event, tip-over spectrum under sinusoidal excitation and soil structure interaction (SSI).
The research also addresses whether the response of DSCs is repeatable under identical ground motions. If the cask response has a relatively large variation (nonrepeatable), the analytical and FE models cannot directly capture this variation. Experimental tests on repeated ground motions showed that the dynamic response is not repeatable, which is the first indicator of chaos or extreme sensitivity to initial conditions. Numerical techniques for chaotic analysis were then implemented, for harmonic excitation, to show that DSCs’ motion is in fact chaotic for certain excitation conditions. This sensitivity was studied in FE models and analytical simulations by varying input parameters by ±1%. This small change resulted in large variation in the response.
|Advisor:||Ibarra, Luis F.|
|Commitee:||Bartlett, Steven F., Coats, Brittany, Pantelides, Chris P., Sanders, David H.|
|School:||The University of Utah|
|Department:||Civil and Environmental Engineering|
|School Location:||United States -- Utah|
|Source:||DAI-B 79/07(E), Dissertation Abstracts International|
|Subjects:||Engineering, Civil engineering|
|Keywords:||Chaotic response, Dry storage casks, Free-standing bodies, Nonrepeatability, Rocking and sliding, Seismic response|
Copyright in each Dissertation and Thesis is retained by the author. All Rights Reserved
The supplemental file or files you are about to download were provided to ProQuest by the author as part of a
dissertation or thesis. The supplemental files are provided "AS IS" without warranty. ProQuest is not responsible for the
content, format or impact on the supplemental file(s) on our system. in some cases, the file type may be unknown or
may be a .exe file. We recommend caution as you open such files.
Copyright of the original materials contained in the supplemental file is retained by the author and your access to the
supplemental files is subject to the ProQuest Terms and Conditions of use.
Depending on the size of the file(s) you are downloading, the system may take some time to download them. Please be